Can Katy Perry continue to top charts without her hit-making producer, Dr. Luke?

Sources say the two had a falling out in January shortly before the Grammys. Since then, the impresario and songwriter has not been promoting Perry or even speaking to her.

Born Lucasz Gottwald, Dr. Luke is a former member of the “Saturday Night Live” band who has 21 No. 1 singles with a series of starlets under his belt and has taken credit for making Ke$ha and restoring Britney Spears‘ career.

Dr. Luke produced Perry’s biggest hits, including “Hot n Cold,” “California Gurls” and “Teenage Dream.” But sources say they likely won’t be working together on her next album. “He’s stopped the hype with her,” an associate of Dr. Luke told us. “She got tired of his records, the same familiar sound, but mostly his attitude. Katy’s a star now, and she’s not going to be told what to do.”

Dr. Luke notably stopped tweeting about Perry in December — although he started again after we called on Friday — and hasn’t mentioned her in recent interviews, where he instead talked about Ke$ha and Spears.

An industry source said, “It’s a red flag if a producer goes completely silent before the Grammys.” Another associate of Dr. Luke told us he may be a musical genius, but his abrasive style can be hard to swallow: “He checks all of his artists. He just curses them out. He thinks he owns them because he made them.”

But some say Dr. Luke isn’t the only one to blame. “It’s a battle of the egos,” one source said. “A lot of people think that without Dr. Luke, Katy’s going to have a big problem. She’s not much of a songwriter or vocalist, and she’s gonna have to start from scratch. You can’t just bring in any producer to make magic. The label is really pushing her to work on another album while she’s hot.”

Dr. Luke’s rep said: “This is ridiculous. They just put the finishing touches on Katy’s newest single, which they created together, in February. They had a great time, and the single is amazing. He wishes Katy nothing but continued success and looks forward to working with her again soon.” Perry’s rep didn’t respond to requests for comment.